The likelihood that illicit drug users will engage in drug-related HIV risk behaviors or suffer adverse drug-related health outcomes varies considerably across neighborhoods. While an emerging line of research has investigated whether particular neighborhood-level characteristics (e.g., presence of dilapidated housing and social disorder) determines neighborhood-level variation in these drug-related behaviors and health outcomes, no research has yet studied whether syringe access (SA) programs or drug-related criminal justice (D-RCJ) activities contribute to neighborhood-level variations in drug-related behaviors and health outcomes among illicit drug users, including injection drug users (IDUs). This absence is striking: (1) SA programs and D-RCJ activities affect patterns of drug-related health behaviors, outcomes, and service use; (2) SA programs and D- RCJ activities are place-based, structural interventions: they are unevenly distributed across neighborhoods and shape the local context in which IDUs use drugs; and (3) D-RCJ activities (and possibly SA programs) exert different impacts on drug-related HIV risk behaviors and health service use among IDUs of different racial/ethnic groups. Explaining racial/ethnic variations in drug-related HIV risk and health service use is a NIDA priority. Current measures of SA programs and D-RCJ activities, however, preclude studying whether these interventions shape geographic variation in drug-related HIV risk behaviors, health outcomes and service use among IDUs. The proposed exploratory study will achieve 3 aims by analyzing existing data: to (1a) Construct new measures of SA programs and D-RCJ activities as place-based, structural, and multidimensional interventions; and (1b) Apply these measures to describe variations in SA programs and D- RCJ activities over time (1995-2006) across NYC's 42 health districts. By applying spatial analysis methods we will calculate, for each NYC health district and year, spatial access to syringes and to SA programs (overall and by program type); and intensity of drug-related arrest, incarceration, and police surveillance. (2) Use multilevel methods to explore whether variations in these measures across health districts and time are related to variations among IDUs in drug-related HIV risk behaviors and health service use across districts and time. (3) Explore if variations in these district-level measures create variations in drug-related HIV risk behaviors and service use, both within and between racial/ethnic groups of IDUs. The proposed project will lay the foundations for future investigations of the ways that SA programs and D-RCJ activities shape neighborhood- level variations in a wide range of health behaviors (e.g., HIV sexual risk), outcomes (e.g., HIV transmission), and service use (e.g., drug treatment entry) among IDU populations in multiple cities. Research based on these measures may provide important insight into how to modify SA programs and D-RCJ activities so as to reduce morbidity and mortality among drug users, their sex partners, and neighbors. Public Health Relevance Statement Rates of drug-related HIV risk behaviors and adverse drug-related health outcomes vary across neighborhoods in a city. No research has yet explored whether syringe access (SA) programs or drug-related criminal justice (D-RCJ) activities affect this neighborhood-level variation. The proposed project will construct measures of SA programs and D-RCJ activities that will allow us to explore whether these programs and activities create neighborhood-level variation in key drug-related health behaviors, outcomes, and service use in a city, and will empirically test whether changes in SA programs and D-RCJ activities in one US city (NYC) are associated with (1) neighborhood-level variation in drug injectors' drug-related HIV risk behaviors and health service use and (2) racial/ethnic variations in these outcomes. Project-created measures of SA programs and D-RCJ activities can be applied to other cities, and can be used to analyze neighborhood-level variations in a wide range of health behaviors, outcomes, and service use among injectors (e.g., sexual risk behaviors, HIV or HCV transmission, drug treatment entry). Research based on these measures may provide important insight into how to modify SA programs and D-RCJ activities so as to reduce morbidity and mortality among drug users, their sex partners, and neighbors. Given concerns that SA programs adversely affect local quality of life, project measures can also be used to empirically test the relationship between SA program presence in a neighborhood and local crime rates and other adverse social outcomes. [unreadable] [unreadable] [unreadable]